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Water: Monitoring & Assessment

Maine Department of Environmental Protection

Last Updated: March 2000

Contact Information

Jeanne DiFranco (project lead for macroinvertebrates)
Maine Department of Environmental Protection
312 Canco Road
Portland, ME 04103
Office: (207) 822-6424
E-mail: Jeanne DiFranco (Jeanne.L.Difranco@state.me.us)


Jan Stevenson (project lead for algae)
Michigan State University
Department of Zoology
203 Natural Science Building
East Lansing, MI 48824-1115
Office: (517) 432-8083
E-mail: Jan Stevenson (rjstev@msu.edu)

Purpose(s) of Project

  • Develop sampling methods for algae and macroinvertebrates.
  • Develop biological criteria for Maine wetlands.
  • Diagnose stressors degrading wetlands.

Project History



Maine Department of Environmental Protection (DEP) initiated the Casco Bay Watershed biological assessment project in 1998 and has completed two years of sampling. The Casco Bay study is a cooperative effort between Jeanne Difranco of Maine DEP and Jan Stevenson of Michigan State University. As of January 2000, Jeanne Difranco and Maine DEP staff have completed preliminary analysis of 1998 macroinvertebrate data and are processing samples from the summer 1999 season. Jan Stevenson has also completed two years of sampling for algae and is working on development of algal protocols and metrics for Maine wetlands.

Study Design


During the summer of 1998, 20 wetlands were sampled in the Casco Bay Watershed. Sampling was repeated in 1999 for 18 of these wetlands, and two new sites were also added. Considerations for site selection included hydrologic regime, distribution of sites, landscape position, disturbance gradient, management significance, and accessibility. All wetlands sampled are semi-permanently or permanently inundated, and range from minimally disturbed potential reference sites to poor quality wetlands.

Which Assemblages are Monitored?

Sampling Methods: Macroinvertebrates

Macroinvertebrates were sampled during the late summer months, July through August. Two different approaches were tested to develop both qualitative and quantitative methods. A site characterization was also performed, including identification of dominant plant species, human disturbance ranking, and collection of water and sediment samples for chemical analysis.

Dip Net – A qualitative, multihabitat sampling approach was tested, with the goal of developing a screening level assessment tool. A standard D-frame net was used to sample all inundated microhabitats at each site, including emergent vegetation, aquatic macrophyte beds, pools, and channels. Samples were "picked" or sorted from detritus in the field. One to several organisms representing each different taxon found were placed into a vial of alcohol until no different taxa were observed.


Stovepipe Sampler – Maine DEP designed their own stovepipe sampler for quantitative samples using a five-gallon bucket with the bottom removed. In this method, the sampler was used to enclose three replicate plots to restrict the movement of organisms. The stovepipe sampler was pressed into the wetland substrate, and the contents of the sampler were then agitated. Vegetation, surface sediment, and a standard volume of water were placed into a sieve bucket. Large pieces of vegetation were washed and discarded; however, finer plant material and detritus were retained. Samples were preserved for later sorting and taxonomic analysis in the laboratory.

Analytical Methods: Macroinvertebrates

Maine DEP has completed preliminary data analysis for the 1998 macroinvertebrate samples, and further analysis is ongoing. Samples from 1999 are currently being processed and identified.

Sampling Methods: Algae


Quantitative and qualitative algae samples were gathered from the same 20 wetland sites as used for macroinvertebrate sampling. Algae from plants, sediments, and the water column were sampled from multiple sites within each wetland and composited into one sample from each habitat. In addition, a multihabitat sample was collected from each site.

Four algae sample types were collected to determine which produced the best indicators. Samples were collected from the water column, plants, and sediments, and across the wetland as a multihabitat sample. Samples were examined microscopically to determine species numbers and relative abundances of different species in samples. Chlorophyll a as an indicator of algal biomass was quantified from a separate water column sample.

For sampling, scissors were used to clip plants off the bottom substrate, a turkey baster was used to collect sediment samples, and a bottle on a short pole or a hand held cup was used to collect the water samples. For the multihabitat sample, a dose from each sample was combined into one container.

Analytical Methods: Algae

Jan is using three disturbance indicators: land use indicator developed by Maine DEP, trophic status indicators (total Nitrogen, total Phosphorus, and chlorophyl a), and hydrologic and sewage chemicals (Ca, Na, Cl). Jan is comparing a suite of algal indicators to determine which types of indicators respond to the three disturbance indicators. The algae indicators include biotic integrity measures such as genus species richness, Shannon diversity, and number of taxa in genera. Jan is also using European algal autoecology information to determine environmental characteristics for the taxa. This information will give autoecological index that shows a relationship to variables such as moisture, organic N, low oxygen, pH, salt, and nutrients.

Lessons Learned


  • Further refinement is needed for the site selection process to resolve classification and data comparability issues.
  • The multihabitat method tested does not work well for collecting representative chironomid taxa.

Associated Maine Websites

Monitoring and Assessment, Maine DEP Bureau of Land and Water Quality Exit EPA Disclaimer

Monitoring & Assessment, Maine DEP Exit EPA Disclaimer

Maine DEP Bureau of Land and Water Quality Exit EPA Disclaimer

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